How Can I Get Gooseneck Trailer With 7-Blade To Work With Motorhome With 7-Way Round Connector?

Updated 08/15/2025 | Published 07/25/2025

Question:

I have a 2025 freightliner 114sd That has a 7 way round connector and a brake controller ABS. And I have a goose neck 40 trailer that has a 7 Way Blade connector with electric brakes. Now someone before me tried to wire the trailer to a 7 way round connector to match the truck, and it doesnt work whatsoever lights and everything works but brakes seem to stay on or shudders on and off constantly. So what is the best way that I can get the truck to work with the trailer. I can't change connector on truck because we use it for our trailer with no issues. any insight on what i can do so we can get this to work so the truck can communicate with the trailer correctly would save my ass and I'd be eternally thankful!

asked by: Bryce M

Expert Reply:

Hey Bryce, thanks for reaching out. It sounds like the 7-round on your gooseneck trailer may not be wired correctly. Have you tried taking a wire tester or multimeter and checking all the wires? If the trailer plug is not pinned correctly to match the RV it would definitely explain the issue you are describing.

Or, if you are sure the 7-blade connector on your gooseneck trailer is wired correctly, you could use the adapter # PK12-724 to bring them together. The adapter really should not be needed though, if the 7-round were wired correctly and functional. I have attached a few diagrams for your reference.

expert reply by: Jesse M

7-way Diagram 1
(click to enlarge)

7-way Diagram 2
(click to enlarge)

Jesse M.

8/15/2025

Hey Bryce, did you have a chance to test the wiring with a multimeter or try the adapter I mentioned? I'm eager to hear how it worked out for you, as it could really help others facing a similar issue!